We had a kid at primary school who no one ever heard speak, it became an urban legend that he was mute, but he was part of the fabric of Riverside, everyone knew he just never said a word, he added colour to the playground, a real odd character. Can't remember actually ever seeing him moving but he just seemed to appear in different situations.
We had a very posh supply one day who was doing the register and he obviously didn't say "here / yes" – the gradual meltdown this supply teacher had was ****ing world class, she could not wrap her head around the Riverside Mute, she probably has to sleep with white noise on now just to escape the PTSD she gets from silence